Just experienced a crash (release version, the one prior to 126.96.36.199).
When I reset the computer (Mac), I saw the following:
My default browser had been Brave, so I don’t know why this dialog box appeared.
I also don’t know what it means, given that Brave is mentioned both to ‘change’ or ‘keep’ the current default browser.
And most browser windows reloaded in duplicate – i.e., the windows and all of their tabs reloaded twice.